Helix swapping leads to dimerization of the N-terminal domain of the c-type cytochrome maturation protein CcmH from Escherichia coli

In the process of cytochrome c maturation, heme groups are covalently attached to reduced cysteines of specific heme-binding motifs (CXXCH) in an apocytochrome c sequence. In Escherichia coli, the CcmH protein maintains apo-protein cysteines in a reduced state prior to heme attachment. We have purified and biophysically, as well as structurally characterized the soluble, N-terminal domain of E. coli CcmH that carries the functionally relevant LRCXXC-motif. In contrast to a recently presented structure of the homologous domain from Pseudomonas aeruginosa, the E. coli protein forms a tightly interlinked dimer by swapping its N-terminal helix between two monomers. We propose that an altered environment of the functional motif may help to discern between the two redox partners CcmG and apocytochrome c

How Fragmentation Can Improve Co-ordination: Setting Standards in International Telecommunications

There is a stark contrast between the way industrial economics asks us to think about standard setting in telecommunications and the way standard-setting is actually organized. On the one hand, leading scholars maintain that standard setting is a natural monopoly. On the other hand, the number of standards organizations for telecommunications is quite large and there is no indication that this number will decrease. The paper analyzes how to resolve this discrep ancy. It argues that there are reasons to believe that the natural monopoly hypothesis is wrong. Under a certain set of conditions which are prevalent in international telecommunications, the distribution of standard setting to a multitude of competing standards organizations is both stable and efficient

Limited clinical relevance of imaging techniques in the follow-up of patients with advanced chronic lymphocytic leukemia: results of a meta-analysis

The clinical value of imaging is well established for the follow-up of many lymphoid malignancies but not for chronic lymphocytic leukemia (CLL). A meta-analysis was performed with the dataset of 3 German CLL Study Group phase 3 trials (CLL4, CLL5, and CLL8) that included 1372 patients receiving first-line therapy for CLL. Response as well as progression during follow-up was reassessed according to the National Cancer Institute Working Group1996 criteria. A total of 481 events were counted as progressive disease during treatment or follow-up. Of these, 372 progressions (77%) were detected by clinical symptoms or blood counts. Computed tomography (CT) scans or ultrasound were relevant in 44 and 29 cases (9% and 6%), respectively. The decision for relapse treatment was determined by CT scan or ultrasound results in only 2 of 176 patients (1%). CT scan results had an impact on the prognosis of patients in complete remission only after the administration of conventional chemotherapy but not after chemoimmunotherapy. In conclusion, physical examination and blood count remain the methods of choice for staging and clinical follow-up of patients with CLL as recommended by the International Workshop on Chronic Lymphocytic Leukemia 2008 guidelines. These trials are registered at http://www.isrctn.org as ISRCTN 75653261 and ISRCTN 36294212 and at http://www.clinicaltrials.gov as NCT00281918